Ratchet



Jan. 7, 1958 c. A. HARLESS 2,818,950

RATCHET Filed Dec. 3, 1952 2 Sheets-sheaf 1 IN VEN TOR.

BY y X Ar'mfimw Jan. 7, 1958 c. A. HARLESS 2,818,950

RATCHET Filed Dec. 3, 1952 2 Sheets-Sheet 2 IN VEN TOR.

nitd

atent ffice 2,818,950 Patented Jan. 7, 1958 RATCHET Charles A. Harless,Riverside, Conn, assignor to R. Hoe (io Inc., New York, N. Y., acorporation of New Application December 3, 1952, Serial No. 323,845

13 Claims. (Cl. 1955-48) This invention relates to improvements inratchet drives.

it is an object of the invention to provide a ratchet drive capable ofoperating with fine increments of movement, with correspondingly smalllost motion, while utilizing relatively coarse and strong ratchet teeth.

A further object of the invention is to provide an enclosed ratchetdrive mechanism, reducing wear from foreign particles, and permittingefficient lubrication.

A still further object of the invention is to provide a ratchet gearconstruction, in which the parts subject to wear are readilyreplaceable, while the Wear is reduced to a minimum.

A ratchet drive embodying the invention in a preferred form will now bedescribed with reference to the accompanying drawing, and the featuresforming the invention will then be pointed out in the appended claims.

In the drawing:

Figure 1 is a view partly in end elevation and partly in section as tothe ratchet mechanism, and is taken on the section line l-l of Figure 2;

Figure 2 is a side elevational view, partly in longitudinal section onthe line 11-11 of Figure 1;

Figure 3 is a detail section taken on the ,line Ill-Ill of Figure 2;

Figure 4- is a detail section on the line IVlV of Figure 2; and

Figure 5 is a view partly in side elevation and partly in central axialsection, showing a drag or braking mechanism employed with the ratchetdriven element.

The ratchet drive of the invention is shown as applied to the driving ofa fountain roller of a printing machine, the fountain roller 1 (Figures2 and 5) being associated with an ink fountain, as indicatedfragmentarily in Figure l, in the usual way. The shaft 3 of the roller 1is rotatably mounted in bearings 5 and 6 carried in supporting members 7and 8. A drive shaft 9 is mounted in a bushing it carried in a framestructure 11, in axial alignment with the roller ll. This shaft 9 isrocked about its axis by a means not shown, that provides for adjustmentof the extent of angular movement imparted to the shaft. A clutchingarrangement and the ratchet drive of the invention form the drivingconnection between shaft 9 and roller 1.

The ratchet drive comprises an internally toothed ratchet gear ring 29,having evenly spaced teeth including surfaces 21 for driving engagementwith the driving pawls, and surfaces 22 for limiting the outwardmovement of the pawls when in driving position. The ring is supported bya face plate and housing member 23 (Figure 2), which is carried on theshaft end 3 of the roller 1, and rotatably couple-cl thereto by a key 24and held thereon by a nut 25. A second annular face plate element 26completes the housing for the ratchet mechanism, the ring it) beingfastened to the two elements 23 and 26 as by means of screws or bolts2'7 The inner faces of the elements 23 and 26 are formed with circular,rounded shoulders or abutments 2t and 29 for rotatably supporting aninner annular drive member 313, which carries the driving pawls. The

member 30 has a number of bores 31 (shown as eight in number) rotatablyreceiving cylindrical shaft sections 32, each of which carries a pawl.The pawls 33 are rectangular plates or pieces received in radial slotsor grooves in the members 32 and held therein as by means of pins 34.The periphery of the member 30 adjacent each bore 31 is cut away, asindicated, to accommodate the required movement of the pawl, and hasfurther bores or sockets 35 accommodating the spring pressed plungers36, which urge the pawls toward engaging or driving position (clockwisein Figure 1).

Internally the member 30 is formed with spline gear teeth 37,cooperating with mating spline gear teeth 38 on a clutch member 39 whichis slidable axially of the shaft 3', and coupled thereto by cooperatingspline gear teeth td and 41. A clutch handle 42 is pivoted on a shaft 43(Figure 2) is connected to the member 39 by the usual clutch ring andyoke, and is provided with a releasable catch member as shown in Figure4, so that the clutch handle may be freed for movement by pushing out ofthe knob 44 and locked in either engaging or disengaging position byreleasing the knob so as to permit pin 45 to engage in either bore 46 or47 in bracket 48 attached to the frame structure 11, which supports theclutch handle or lever 42. Outwardly of the spline teeth 38, the clutchmember 39 has a circular hub 39', the annular face plate 26 fittingclose around this hub to provide an efiective oil housing enclosure.

A manually operable clutch handle 5i (Figure 2) may also be provided,being rotatably mounted on a hub of the member 23 and having a pawl 51(Figure 3) adapted to engage in a ring 52 provided with ratchet teeth,and which is fixed to the ratchet housing member 23 as by means of bolts53.

While the ratchet drive of the invention is not limited to use withdriven elements equipped with drag or braking mechanism, it possessesparticular advantage in such use. A drag for the .roller 1 is shown inFigure 5, and comprises a housing structure formed of elements 60 and 61bolted to the frame element 8, and including friction plates 62 and 63held from rotation by pins 64 and 65. Cooperating annular frictionelements 66 and 6? are mounted on the shaft end 4 (Figure 5) androtatably coupled thereto by keys 68. Springs 79 between the elements 66and 67 urge them apart axially against the plates 62 and 63, creatingthe desired friction for preventing overrunning of the roller 1 byreasonof its inertia.

The number of teeth on the wheel 2i! is preferably related to the numberof pawls 33, so as to obtain a fine adjustment or increment of movement,and so as also to reduce and equalize wear as far as possible. Thisresult may be achieved by utilizing evenly spaced ratchet teeth andevenly spaced pawls, the number of teeth not being an integral multipleof the number of pawls, so that the angular interval between adjacentpawls exceeds an inte gral multiple of the angular interval betweenadjacent teeth by a fraction of a tooth interval. In the structureshown, there are eight pawls 33 spaced equally around the member 3t),and, hence, separated by 45 from each other. Ninety evenly spaced teethare provided on the inner surface of the ring 20, the tooth spacing,accordingly, being 4. Assuming a given pawl to be in driving engagementwith a tooth (as in the case of the uppermost pawl in Figure 1), itfollows that the next tooth in order (clockwise in Figure 1) will be 1from driving engagement with a tooth of the wheel 20; the next pawl willbe 2 from engagement; the third pawl will be 3 from engagement; whilethe fourth pawl, or lowermost pawl in Figure 1, will again be in drivingengage ment with a tooth of the wheel 26). If it should happen at anygiven time in the operation of the ratchet that no pawl is in drivingengagement with a tooth of the ring 20, it will be apparent that theamount of rotation of the inner driving member 30 required to bring apawl into such engagement, will always be less than 1. Thus, with teethwhich are spaced 4 apart and may be correspondingly rugged, an incrementof movement of maximum lost motion of 1 is obtained.

it is preferred that the number of pawls and teeth be even, so that apair of diametrically opposite pawls will engage. The reaction of thepawls against the member 30 will thus be substantially a pure couple,involving no tendency to shift the member transversely of its axis ofrotation, so that wear of the bearing surfaces supporting this member inthe face plates is reduced to a minimum. However, an odd number of teethor an odd number of evenly spaced pawls may be used and thereby obtainmuch finer increments of movement of the roller .1.

Assuming no overrunning of wheel 2:; by reason of inertia of the drivenelement 1, there will generally be a shifting at each stroke of theratchet, of the pawls which are in driving engagement with teeth of thewheel 20, and also of. the teeth which are engaged. For example, ifFigure 1 be taken to represent the completion of a ratchet strokethrough of are, it will be apparent that following the idle stroke(clockwise) of the inner drive member 39, the teeth of the pawls whichengage on the next working stroke will not be those which engaged uponthe previous stroke, but the adjacent pawls in the clockwise direction,etc. As the ratchet drive is adjusted from time to time for differentangles of stroke, the relationship between the pawls and the teeth ofthe wheel 29 continually changes, the various pawls operating sometimesto engage with one tooth and then another, and the order of engagementof the pawls from stroke to stroke varying with the angular adjustment.Wear is thus thoroughly equalized.

The pawls are preferably rectangular, as shown in Figure 1, and aremounted radially of their supporting shafts 32. The driving thrust thusdoes not tend to wedge the pawls into the teeth openings of the member29, nor does it tend to dislodge them. The tips of the pawl plates 33are preferably case hardened to reduce wear to a minimum, and theratchet wheel is also suitably hardened.

By following around Figure 1, starting with the uppermost pawl, therelative movement between pawls and ratchet teeth on the idle strokewill be apparent, and it will be observed that this is a slidingmovement involving but little wear, as the pressure exerted by thespring plungers as may be comparatively light. It will also be observedthat when the edges of the plates 33 or of the teeth in the ratchetwheel 21) are slightly worn, the operation will not be impairedmaterially. Should objectionable wear occur after long use, the ratchetis readily reconditioned or repaired by merely replacing plates 33 orthe wheel 20, or both, as may be required.

What is claimed is:

1. A ratchet drive comprising a ratchet ring having an even number ofevenly spaced ratchet teeth, a cooperating rotatable pawl member havingevenly spaced pawls arranged in diametrically opposite pairs forcooperating with the said teeth, the spacing between adjacent pawlsexceeding an integral multiple of the spacing between the teeth, by anamount equal to the spacing between adjacent teeth divided by the numberof pairs of pawls.

2. A ratchet drive comprising an outer ring having an even number ofevenly spaced internal ratchet teeth, an inner member having evenlyspaced pawls arranged in diametrically opposite pairs for cooperatingwith the said teeth, the spacing between adjacent pawls exceeding anintegral multiple of the spacing between the teeth, by an amount equalto the spacing between adjacent teeth divided by the number of pairs ofpawls.

A ratchet drive according to claim 2, in which the outer ring has ninetyteeth and the inner member has eight pawls.

4. A ratchet drive mechanism comprising an outer ring having a pluralityof evenly spaced internal ratchet teeth, means cooperating with theouter ring to form a housing, an inner ratchet member having a pluralityof sets of evenly spaced pawls, the number of pawls being related to thenumber of teeth so that one pawl of each set ena tooth simultaneouslywith one pawl of each other set, means formed on the inner ratchetmember and the housiu" for rotatably supporting the inner ratchet memberin the housing, means for mounting the housing upon a shaft forsupporting the ring and inner ratchet member in spaced relation to theshaft end, a clutch member slidable in the inner member, and means formounting the clutch member slidably on the end of a shaft aligned withthe first mentioned shaft, the housing having an opening accommodatingthe said clutch member.

5. A ratchet drive mechanism comprising an outer ring having an evennumber of evenly spaced internal ratchet teeth, means cooperating withthe outer ring to form a housing, an inner ratchet member having aplurality of pairs of diametrically opposite and evenly spaced pawls,the number of pawls being related to the number of teeth so that onesuch pair of pawls engages a pair of ratchet teeth simultaneously, meansformed on the inner ratchet member and the housing for rotatablysupporting the inner ratchet member in the housing, means for mountingthe housing upon a shaft for supporting the ring and inner ratchetmember in spaced relation to the shaft end, a clutch member slidable inthe inner member, and means for mounting the clutch member slidably onthe end of a shaft aligned with the first mentioned shaft, the housinghaving an opening accommodating the said clutch member.

6. A ratchet drive mechanism comprising an outer ring having internalratchet teeth, means cooperating with the ring to form front and backhousing walls, an inner ratchet member carrying pawls for cooperatingwith the said teeth, a shaft rotatably coupled to the said inner ratchetmember, and means formed on the inner ratchet member and housing meansfor rotatably supporting the said inner member in the housingindependently of the said shaft.

7. A ratchet drive mechanism comprising an outer ring having internalratchet teeth, a pair of face plates attached to the ring and forming anoil housing therewith, one of the said face plates having means forattaching to a shaft end in supported and driving relation thereto, theother of the said face plates having an axial circular opening, an innerratchet member carrying pawls for cooperating with the said teeth, meansformed on the inner ratchet member and face plates for rotatablysupporting the said inner member in the housing, and a drive member forthe inner ratchet member passing through the said circular opening andhaving a circular hub fitting therein for completing the oil housing.

8. A ratchet drive member according to claim 7, in which the drivemember and inner ratchet member having cooperating splines andcomprising also means mounting the drive member slidably for engagingand disengaging with the inner ratchet member.

9. A ratchet drive mechanism comprising an outer ring having internalratchet teeth, a pair of face plates attached to the said ring forforming a housing, means for mounting one of the said face plates on ashaft for supporting the ring therefrom and forming a drive connectionbetween the ring and the said shaft, an internal ratchet drive membercarrying pawls in cooperating relation to the teeth of the said ring,means for rotatably supporting the said inner ratchet member in thehousing, an axially movable clutch member slidably positioned within theinner drive member, the clutch member and inner ratchet member havingcooperating spline.teeth,.the clutch memher having also a circular hub,and the second said face plate having a circular opening fitting aroundthe same to complete an oil housing.

10. A ratchet drive mechanism comprising a ring having internal ratchetteeth, face plates attached to the ring to form a housing, an innerdrive member rotatably carried in the housing and having a plurality ofaxial bores spaced around its periphery and openings from said boresthrough its periphery, pawl members comprising short shafts carryingpawl plates and rotatably and slidably carried in the said bores withthe plates projecting through the said openings in cooperating positionwith relation to the teeth, the face plates having bearing surfaces forthe ends of the said short shafts, for maintaining them in predeterminedposition axially of the inner member.

11. A ratchet drive mechanism according to claim 10, in which the shortshafts have slots receiving the pawl plates and transverse pins holdingthe plates Within the slots.

12. A ratchet drive mechanism according to claim 10, in which the innermember has bores extending transversely of the first mentioned bores andcomprising spring pressed plungers within the said transverse bores andengaging the pawl plates for urging them outwardly toward the outerring.

13. A ratchet drive mechanism comprising an outer ring having aplurality of evenly spaced ratchet teeth, means coperating with theouter ring to form a housing, a ratchet member having a plurality ofpawls supported to engage the ratchet teeth, a shaft rotatably coupledto the said ratchet member, and means formed on the ratchet member andthe housing for rotatably supporting the ratchet member in the housingindependently of the said shaft.

References Cited in the file of this patent UNITED STATES PATENTS1,122,146 Mitchell Dec. 22, 1914 1,799,987 Rauen Apr. 7, 1931 1,966,290Furgason July 10, 1934 2,064,230 Starr Dec. 15, 1936 2,079,527 Raven May4, 1937 2,153,556 Gartin Apr. 11, 1939

